Weddell seals spend about 90% of their time submerged, making them a tricky animal to study. Before Davis developed a special camera, scientists could only speculate about the seals' lives below the ice.

During the winter, the sea ice off Antarctica covers an area so big that it's actually the largest continuous habitat on Earth. The algae that live there produce 25 percent of all oxygen on the planet.

Antarctica's water is so clear that organisms have problems finding food. "It's like parents having to tell their young, 'We're not going to be able to feed you until Christmas, so hold your breath,'" says Donal Manahan.